JP2742846B2 - Rolling method of steel bars by 4 roll mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling steel bars using a four-roll mill. More specifically, the present invention relates to a rolling method for sizing a metal material (including a bar and a wire) having a circular cross section with a four-roll mill.

[0002]

2. Description of the Related Art In recent years, a rolling method using a four-roll mill has been proposed in order to increase rolling accuracy (roundness).
As shown in FIG. 6, the roll hole diameter of the conventional 4-roll mill is a perfect circle part a in the range of 45 to 50 degrees centered on the center of each of the rolls 1 and 2, and an arc or a circle larger than a perfect circle is formed at both ends. A straight run-out portion b is formed, and the second pass (II in FIG. 6) is performed with respect to the roll 1 in the first pass (I in FIG. 6).
Roll 2 is arranged to be rotated 45 degrees about the pass line. The material to be rolled is passed and sized in the first pass (I in FIG. 6) and the second pass (II in FIG. 6). In this rolling method, the round part a of the roll 1 in the first pass (I in FIG. 6) and the roll 2 in the second pass (II in FIG. 6)
There is an advantage that the roundness of the rolled material is increased because the round portion a of the wrapped portion is wrapped.

[0003]

However, there is a problem that the conventional rolling method cannot increase the area reduction rate.
As shown in FIG. 7, the hatched portion between the roll surface 3 of the roll hole diameter (including the perfect circle portion a and the relief portion b) and the outline 11 of the material is a portion where the cross-sectional area is reduced by rolling. When the area is large, the area reduction rate is high, and when the area is small, the area reduction rate is low. By the way, in order to perform rolling with a high reduction in area, a material having a diameter larger than the maximum diameter of the relief portion b of the roll 1 (the outer line is defined as
When rolling is carried out (shown by 11a), a bite 12 is generated in the roll gap c as shown in FIG. 8, and this bite 12 does not completely disappear even if it is rolled again. Therefore, such a rolling method cannot be adopted. As shown in FIG. 7, the limit at which the bite 12 does not occur is that the material diameter D is
In this case, the area reduction rate depends on the area surrounded by the rolling surface 3 and the outer shape line 11 of the material. And the relief b, and the dimensional difference h between the rolling surface 3 and the outer shape line 11
As long as it does not increase, the area reduction rate does not exceed 10%.

As described above, in the conventional rolling method, since the area reduction rate is low, it is necessary to arrange a large number of rolls at a fine size pitch. For example, a round bar steel of 131 kinds of sizes is rolled between 12.7 and 120 mm. In that case, 131 for 2 rolls
In the case of the conventional four rolls, 50 to 60 types of roll-type rolls were required.

In view of such circumstances, the present invention provides a rolling method capable of rolling a large number of bar steel materials with a small number of rolling rolls while maintaining high roundness while maintaining the roundness substantially equal to that of the conventional rolling method. The purpose is to provide.

[0006]

The rolling method according to the present invention comprises:
Using a rolling machine in which the 4th roll mill of the 2nd pass is arranged at a 45 ° inclination about the pass line with respect to the 4th roll mill of the pass, the roll spacing is adjusted, and a circular cross section of several sizes is formed by rolls having the same roll hole diameter. A method of rolling a steel bar to be rolled into a finished material, characterized in that the following roll hole diameter is used. As shown in FIG. 1 (I), the roll hole radius R1 in the first pass is 1.1 to 2 times the material radius r. Since the roll hole die radius R1 of the present invention is larger than the rolling surface 3 (see FIG. 7) of the conventional roll, the material outline 11
And the dimensional difference h increases, and the rolling area S1 indicated by oblique lines increases. Therefore, the area reduction rate can be increased. The numerical range of the roll hole radius R1 of the present invention (1.1)
r to 2r), the larger the numerical value is, the larger the dimensional difference h is.
Is increased, so that the area reduction rate is naturally increased. The lower limit of the roll hole radius R1 is defined in relation to the reduction in area, and if the lower limit is less than 1.1r, it is not preferable because the reduction in area cannot be expected. Further, the upper limit is defined from the relationship with the roundness. If the upper limit exceeds 2r, the deviation in diameter becomes large, and the roundness decreases, which is not preferable. Only between the upper limit value and the lower limit value of the present invention, a high area reduction rate of about 20% can be achieved while maintaining the roundness almost equal to that of the conventional rolling method.

In the first pass, the circular material outer shape 11 is rolled into a non-circular cross section (see reference numeral 21 in FIG. 1 (II)). 1,1
(The distance between centers) is rolled so as to have the same diameter as the finished diameter D3. As shown in FIG. 1 (II), the roll 2 in the second pass has a roll hole radius R2 that is the same as the largest diameter finish material D3 of the finish materials of the several sizes, that is, a perfect circle. In the second pass, the material of the non-circular cross section after one pass (see reference numeral 21) is finish-rolled into a circular cross section. Reference numeral S2 is an area reduced in the second pass. In this second pass, 1
The region f where the rolled surface of the pass remains as it is is small, and therefore, the roundness is slightly inferior to the conventional rolling method, but does not fall below the accuracy required for practical use. And 2
Since the roll hole radius R2 of the pass uses the maximum radius of a size that can be rolled in the same hole shape, by changing the distance S between the roll cores, the material having a finish radius smaller than the maximum radius can be rolled. can do. In this case, for a material having a finished diameter smaller than the roll die radius R2, an eccentricity difference δ, that is, a dimensional difference between the roll die radius R2 and the finished diameter D3 is generated. It does not reduce the circularity beyond a practically acceptable range.

[0008]

As described above, the cross-sectional area of the material is greatly reduced in the first pass, and the finished material of several sizes is rolled with the same roll in the second pass. Can be greatly reduced, so that the number of roll hole types can be greatly reduced.

[0009]

Next, the rolling method of the present invention will be described with reference to FIGS. In each of the figures, the upper half shows the first pass (I) and the lower half shows the second pass (II) with the center horizontal line as the boundary, D1 is the material diameter, D3 is the finished material diameter, and 11 is the material outer shape. Line, 21 is the outline of the material after 1 pass and before 2 passes, 31 is the outline of the finished material, R1 is the radius of the roll hole of the first pass, R2 is the radius of the roll hole of the second pass, and δ is the bias. It is a diameter difference.

Embodiment 1 The rolls 1 and 2 shown in FIGS. 2 and 3 have the same hole diameter, and the roll hole radius R1 in the first pass is 14.3 mm and the material diameter is 1 mm.
It is 1.765 times the radius (8.1 mm) of 6.2 mm, and the roll hole radius R2 in the second pass is the same as the maximum finished diameter, that is, 15.6 mm of a perfect circle. Rolling example 1 using the above roll
And Rolling Example 2 are shown below. Rolling example 1 (see FIG. 2)
This is an example of rolling a round steel bar having a material diameter D1 of 16.2 mm to a finished diameter D3 of 14.3 mm. S1 reduces the area reduced in the first pass (I), and S2 reduces the area in the second pass (II). The part is shown. Inlet and Outlet material diameters in each pass (unit: m
Table 1 shows m), the change in cross-sectional area (unit: mm ² ), and the area reduction rate by numerical values. Table 1 Pass No: Inlet diameter Outlet diameter Cross- sectional area change Reduction area 1 pass: 16.2 (15.06) 206.12−178.04 = 28.08 0.1362 2 pass: (15.06) (14.37) 178.04−162.09 = 15.95 0.0896 Note: () The numerical value in the above is a nominal diameter converted into a perfect circle from the cross-sectional area after rolling. Rolling example 2 (see FIG. 3) is an example in which the same-diameter material is rolled to a finished diameter of 15.6 mm using the rolls 1 and 2 described above.
Indicates a portion reduced in the first pass (I), and S2 indicates a portion reduced in the second pass (II). Change in material diameter (unit: mm) and cross-sectional area (unit: mm) on the inlet and outlet sides in each pass
Table 2 shows numerical values of mm ² ) and the area reduction rate. Table 2 Pass No: Inlet diameter Outlet diameter Cross- sectional area change Reduction area 1 pass: 16.2 (15.99) 206.12−200.89 = 5.23 0.0254 2 pass: (15.99) (15.6) 200.89−191.13 = 9.76 0.0486 Note: () The numerical value in the above is a nominal diameter converted into a perfect circle from the cross-sectional area after rolling.

In the rolling example 1, since the reduction rate of the first pass is as high as about 14%, the material diameter can be reduced from 16.2 mm to 14.3 mm in only two passes. Rolling example 2 is an example in which the finished diameter of 15.6 mm is obtained by widening the center distance S between the rolls. In this case, the rolling amount is small, and the reduction in area in the first pass is also about 2.5.
Rolling is set as low as%. In the case of rolling example 1, 2
Since the finished diameter D3 of the pass is smaller than the roll hole radius R2, an eccentricity difference δ of only 0.092 mm / radius occurs, but this does not lower the roundness to a practically acceptable range. In the case of Rolling Example 2, the finished diameter D3 of the second pass is the same as the roll hole radius R2, so there is no eccentricity difference δ, and the roundness is high. The rolling example 1 has a minimum finishing diameter that can be sized by the rolls 1 and 2, and the rolling example 2 has a maximum finishing diameter that can be similarly sized. Finishing diameter between the minimum and maximum finishing diameters, for example, 14.5mm, 1
Finished diameters such as 4.7mm, 15.0mm, 15.5mm are also available between roll cores.
Can be naturally obtained by adjusting. Therefore, in the conventional rolling method, two types of roll dies were required for two rolls, and two types of roll dies were required for four rolls. In the present invention, one type of roll dies was used for each size. Round bars can be sized.

Example 2 The rolls 1 and 2 shown in FIGS.
The radius R1 of the roll hole die in the first pass is 20 mm, 1.74 times the radius (11.5 mm) of the material diameter of 23 mm, and the radius R2 of the roll hole die in the second pass is the same as the maximum finished diameter, that is, 22.4 of a perfect circle.
mm. Rolling examples 3 and 4 using the above rolls are shown below. In rolling example 3 (see FIG. 4), the material diameter D1 is
This is an example of rolling a 23 mm round steel bar to a finished diameter D3 of 20.0 mm, where S1 is a portion reduced in the first pass (I) and S2 is 2
The part to be reduced at the pass (II) is shown. Table 3 shows the numerical values of the material diameter (unit: mm), the cross-sectional area change (unit: mm ² ), and the area reduction rate of the entrance side and the exit side in each pass. Table 3 Pass No: Inlet diameter Outlet diameter Change in cross-sectional area Reduction area 1 pass: 23.0 (21.08) 415.48−349.10 = 66.38 0.1598 2 pass: (21.08) (20.10) 349.10−317.46 = 31.64 0.0906 Note: () The numerical value in the above is a nominal diameter converted into a perfect circle from the cross-sectional area after rolling. Rolling example 4 (see FIG. 5) is an example in which the same-diameter material is rolled to a finished diameter of 22.4 mm by the rolls 1 and 2 described above.
Indicates a portion reduced in the first pass (I), and S2 indicates a portion reduced in the second pass (II). Change in material diameter (unit: mm) and cross-sectional area (unit: mm) on the inlet and outlet sides in each pass
Table 2 shows numerical values of mm ² ) and the area reduction rate. Table 4 Pass No: Inlet diameter Outlet diameter Change in cross-sectional area Reduction area 1 pass: 23.0 (22.82) 415.48−409.14 = 6.34 0.0153 2 pass: (22.82) (22.4) 409.14−394.08 = 15.06 0.0368 Note: () The numerical value in the above is a nominal diameter converted into a perfect circle from the cross-sectional area after rolling.

In rolling example 3, since the reduction in area in the first pass is as high as about 16%, the material diameter can be reduced from 23.0 mm to 20.0 mm in only two passes. Rolling Example 4 is an example in which the finished diameter of 22.4 mm was obtained by widening the center distance S between the rolls. In this case, the rolling amount was small, and the reduction in area in the first pass was also about 1.5.
Rolling is set as low as%. In the case of rolling example 3, 2
Since the finished diameter D3 of the pass is smaller than the roll hole radius R2, the eccentricity difference δ occurs by only 0.153 mm / radius, but this does not reduce the roundness to a practically acceptable range. In the case of rolling example 4, the finished diameter of the second pass is the roll hole radius R2.
Since the diameter is the same as that of, there is no eccentricity difference δ, and the roundness is high. Rolling Example 3 has a minimum finishing diameter that can be sized by the roll, and Rolling Example 4 has a maximum finishing diameter that can also be sized. Finish diameters between the minimum and maximum finish diameters, e.g. 20.6mm, 21.0mm, 21.4
mm, 21.8 mm, 22.0 mm, 22.2 mm, 22.3 mm, etc. can be naturally obtained by adjusting the roll core spacing S in FIGS. Therefore, in the conventional rolling method, two types of roll holes were required in the case of two rolls, and three types of roll holes were required in the case of four rolls. A round bar of each size can be sized in a mold.

Other Embodiments The description in the above embodiment can be similarly applied to the case of rolling round bars of different material diameters, for example, 36.0 to 39.0.
Round bars of 8 sizes between mm can be sized with rolls of the same roll hole diameter, and round bars of 3 sizes between 72.0 to 75.0 mm can be sized with rolls of the same roll hole diameter. Therefore, even when rolling round bars of 131 sizes between 12.7 and 120 mm, it is sufficient to use only 25 to 30 types of rolls.

[0015]

As described above, according to the present invention, while maintaining the roundness substantially equal to that of the conventional rolling method, a high surface reduction rate is obtained, and a large number of steel bars are rolled with a small number of rolling rolls. Therefore, the number of types of roll holes before and after the finishing can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a roll 1 in a first pass (I) and a roll 2 in a second pass (II) in the rolling method of the present invention.

FIG. 2 shows (I) in Rolling Example 1 of Embodiment 1 of the present invention.
Is an explanatory diagram showing a first pass, and (II) is an explanatory diagram showing a second pass.

FIG. 3 shows (I) in Rolling Example 2 of Embodiment 1 of the present invention.
Is an explanatory diagram showing a first pass, and (II) is an explanatory diagram showing a second pass.

FIG. 4 shows (I) in Rolling Example 3 of Embodiment 2 of the present invention.
Is an explanatory diagram showing a first pass, and (II) is an explanatory diagram showing a second pass.

FIG. 5 shows (I) in Rolling Example 4 of Embodiment 2 of the present invention.
Is an explanatory diagram showing a first pass, and (II) is an explanatory diagram showing a second pass.

FIG. 6 is an explanatory view of a roll 1 in a first pass (I) and a roll 2 in a second pass (II) in a conventional rolling method.

FIG. 7 is an explanatory diagram of a limit of the start of rolling in a conventional rolling method.

FIG. 8 is an explanatory diagram of a problem in a conventional rolling method.

[Explanation of symbols]

1 roll 2 rolls
3 Rolling surface D1 Material diameter D3 Finished diameter
11 Material outline 21 Material outline after 1 pass 31 Finished material outline R1 Roll 1 hole radius R2 Roll 2 hole radius

Claims (1)

(57) [Claims] A roll having the same roll hole diameter by adjusting a roll interval by using a rolling machine in which a 4-roll mill of a second pass is arranged at a 45-degree inclination about a pass line with respect to a 4-roll mill of a first pass. Is a method of rolling a steel bar which is rolled into a finished material having a circular cross section of several sizes by using a roll having a roll die diameter of 1.1 to 2 times the material radius. Rolled so that the minimum transfer diameter of the subsequent non-circular cross section is the same as the finished diameter, and the second pass, the roll hole diameter is the same as the largest diameter finish material of the several sizes of finish materials. A method for rolling a steel bar by a four-roll mill, wherein the steel bar is rolled to a circular cross section having a finished diameter by using a finished roll.